2018-01-15
Kenneth Wiersema
Kenneth Wiersema12:45 PM

@Kenneth Wiersema has joined the channel

Rose Bandrowski
Rose Bandrowski12:45 PM

@Rose Bandrowski has joined the channel

Kenneth Wiersema
Kenneth Wiersema12:45 PM

@Kenneth Wiersema set the channel purpose: Make an intake

Rose Bandrowski
Rose Bandrowski1:40 PM

Mark Tarlton
Mark Tarlton1:40 PM

@Mark Tarlton has joined the channel

Aiden Grayson
Aiden Grayson1:40 PM

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Julian Bonifaci
Julian Bonifaci1:40 PM

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brian_bonifaci
brian_bonifaci1:40 PM

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Kaedric Holt
Kaedric Holt1:40 PM

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Grant
Grant1:41 PM

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Rose Bandrowski
Rose Bandrowski1:57 PM

Chassis: 27.5” x 32.3”

Cruz Strom
Cruz Strom2:57 PM

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Enrique Chee
Enrique Chee3:09 PM

@Enrique Chee has joined the channel

Riyadth Al-Kazily
Riyadth Al-Kazily4:29 PM

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Justice James
Justice James4:33 PM

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Will Hobbs
Will Hobbs4:49 PM

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Randy Groves
Randy Groves4:49 PM

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Peter Hall
Peter Hall5:12 PM

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Harper Nalley
Harper Nalley5:24 PM

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Binnur Alkazily
Binnur Alkazily5:39 PM

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Kirsten Martel
Kirsten Martel6:30 PM

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John Sachs
John Sachs7:05 PM

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Declan Freeman-Gleason
Declan Freeman-Gleason7:34 PM

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Micah C. Glasby
Micah C. Glasby8:22 PM

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Darwin Clark
Darwin Clark9:09 PM

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Jack Chapman
Jack Chapman9:33 PM

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Bill Bandrowski
Bill Bandrowski9:41 PM

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2018-01-16
Dana Batali
Dana Batali8:36 AM

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Ethan Rininger
Ethan Rininger11:43 AM

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Rose Bandrowski
Rose Bandrowski6:07 PM

If you get time tonight, perhaps looking into the grabbers and arms that Robot in Three days used will be useful for us tomorrow. I'll see about posting some videos here tonight

Rose Bandrowski
Rose Bandrowski6:24 PM

We have around 12" we're going to have to extend with Paul's current scissor design to be able to place a block on the second level of cubes. So keep that in mind. Also that number isn't final.

Edgar Flynn
Edgar Flynn6:24 PM

@Edgar Flynn has joined the channel

John Sachs
John Sachs9:53 PM

Rose Bandrowski
Rose Bandrowski9:58 PM

Thank you!!

2018-01-17
Kaedric Holt
Kaedric Holt4:14 PM

A link to a helpful Chief Delphi threac from another team. https://www.chiefdelphi.com/forums/showthread.php?t=161165&highlight=belts+intake

Rose Bandrowski
Rose Bandrowski4:17 PM

Great example of what we've been focusing on

Rose Bandrowski
Rose Bandrowski5:11 PM

Update: the mounting place is 1.5" from the top of the second layer of cubes when an opponent is winning

Robert Galvin
Robert Galvin7:02 PM

@Robert Galvin has joined the channel

2018-01-18
Rose Bandrowski
Rose Bandrowski8:09 PM

Rose Bandrowski
Rose Bandrowski8:09 PM

Working out how far the grabber can extend and be inside the 16" perimeter

Rose Bandrowski
Rose Bandrowski8:10 PM

currently its in contact with the cube as much as possible and still within 16"

Rose Bandrowski
Rose Bandrowski8:10 PM

39.5 is the angle the grabber is at (from horizontal)

Rose Bandrowski
Rose Bandrowski8:10 PM

Not necessarily final, however a start

Rose Bandrowski
Rose Bandrowski8:13 PM

Redrawing in autocad since you can't see anything I'm doing in fusion sketch

Rose Bandrowski
Rose Bandrowski8:29 PM

Rose Bandrowski
Rose Bandrowski8:29 PM

Here's an alternative sketch with a cut out of the bumpers

Rose Bandrowski
Rose Bandrowski8:29 PM

That degree angle from the horizontal is 54 degrees

Rose Bandrowski
Rose Bandrowski8:38 PM

Rose Bandrowski
Rose Bandrowski8:38 PM

This is without the bumper cut out

Rose Bandrowski
Rose Bandrowski8:38 PM

The degree angle there is about 38 degrees

Rose Bandrowski
Rose Bandrowski8:39 PM

as you can see, if we have a cutout from the bumper that is relatively cube shape we get more surface area to grip the cube within that 16" restriction

Rose Bandrowski
Rose Bandrowski8:41 PM

@brian_bonifaci @Mark Tarlton

Kirsten Martel
Kirsten Martel8:44 PM

@Kaedric Holt Please be sure to get Rose’s drawings/models and model this up. We’ll add it to the full robot model tomorrow and see how it all fits together with the top of the scissor.

Rose Bandrowski
Rose Bandrowski8:44 PM

I can send you a file that you can dimension from

Rose Bandrowski
Rose Bandrowski8:44 PM

@Kaedric Holt

Kaedric Holt
Kaedric Holt8:47 PM

Gotcha, I'm working on the CAD now

Rose Bandrowski
Rose Bandrowski8:54 PM

It's in autocad, can you work with that or do you want me to send you a dimensioned picture?

Kaedric Holt
Kaedric Holt8:56 PM

Dimensions would be nice, ya. Thanks

Rose Bandrowski
Rose Bandrowski8:57 PM

Rose Bandrowski
Rose Bandrowski8:58 PM

The PDF I sent you is annoying, but it's basically just the length of the plate and the arm that's holding it. I can give you a better photo if necessary.

Kaedric Holt
Kaedric Holt9:02 PM

It's fine, I'm going to trust ya math and finish building it then.

Rose Bandrowski
Rose Bandrowski9:02 PM

Okay

Kaedric Holt
Kaedric Holt9:18 PM

Is the length of the arm the same w/ full bumpers?

Rose Bandrowski
Rose Bandrowski9:18 PM

no

Rose Bandrowski
Rose Bandrowski9:18 PM

It's longer

Kaedric Holt
Kaedric Holt9:18 PM

K, I can figure it out

Rose Bandrowski
Rose Bandrowski9:19 PM

I think it makes more sense to have a bumper cut out so design it with that

Rose Bandrowski
Rose Bandrowski9:19 PM

We can confirm with the team tomorrow if we can have space cut out of the bumpers but if you can, design it that way now

Kaedric Holt
Kaedric Holt9:19 PM

I'ma design both

Rose Bandrowski
Rose Bandrowski9:19 PM

Okay

Micah C. Glasby
Micah C. Glasby10:10 PM

I looked at some slides we could use. Here are a few of our options.

2018-01-19
Riyadth Al-Kazily
Riyadth Al-Kazily9:53 AM

I posted this video in the engineering channel last week, but it looks like it may be useful to you here. I have a couple of drawer slides you can have (8 inches long, I think), if they would be useful.

Riyadth Al-Kazily
Riyadth Al-Kazily9:54 AM

Terry Shields
Terry Shields10:26 AM

@Terry Shields has joined the channel

Terry Shields
Terry Shields10:42 AM

Posting this question in #programming and #intake-grabber ...Besides vision capability, has anyone seen other teams provide the driver with a "successful capture" indication when the robot clutches a cube?

Rose Bandrowski
Rose Bandrowski10:54 AM

@Terry Shields what do you mean? Basically a green light or some sort of indicator that says the cube is successfully captured?

Rose Bandrowski
Rose Bandrowski10:55 AM

We haven't considered an indicator, no

Rose Bandrowski
Rose Bandrowski10:56 AM

I'd like to consider it though. I don't have an extensive knowledge of electronics so I'll need guidance regarding the sort of system that will allow for such an indication

Terry Shields
Terry Shields11:26 AM

@Rose Bandrowski I was just going through a list of robot input/outputs in my head for the #electronic-pneumatics team. Was wondering if the driver, working on the far side of the field, would need some positive feedback that the cube was successfully in our grasp so they can drive away. If we can do it all with vision, great. If not, then perhaps a pressure contact/switch of some sort should be considered. The driver is going to handle what? 6 to 8 cubes in a match? We want to eliminate as much guess work as possible in those precious few opportunities.

Rose Bandrowski
Rose Bandrowski11:58 AM

@Terry Shields I agree that sounds like a good idea

Dana Batali
Dana Batali11:58 AM

@Terry Shields - i would wager that a feedback switch would be a more guaranteed method to ensure drivers that all is good.

Rose Bandrowski
Rose Bandrowski11:58 AM

there should ample space for a positive feedback system as well

Rose Bandrowski
Rose Bandrowski11:58 AM

Either on the backplate or maybe the arms

Rose Bandrowski
Rose Bandrowski11:59 AM

There will likely be pressure from both though even if the cube isn't grabbed successfully so I say it needs some set amount of pressure

Rose Bandrowski
Rose Bandrowski11:59 AM

(Is that possible?)

Rose Bandrowski
Rose Bandrowski12:00 PM

Also, we have a lower intake system (harvester) that is meant for alignment so there is less work from the driver

Rose Bandrowski
Rose Bandrowski12:00 PM

and will increase the success rate of pick up from the scissor lift grabber/arm

Rose Bandrowski
Rose Bandrowski12:23 PM

@Paul Vibrans I how do you plan on being able to pivot the grabber arm? using the winch system? how should I spec out a motor for that?

Paul Vibrans
Paul Vibrans12:23 PM

@Paul Vibrans has joined the channel

Paul Vibrans
Paul Vibrans12:30 PM

The grabber pivots just the way the one on the prototype does, with wires that go around pulleys to the bottom. At the bottom there are two pulleys that don't move up and down, spaced 12 inches apart. The wires that go between these pulleys are attached to a slide that is moved by a lead screw, a custom made linear actuator, that is turned by a CIM motor. The parts except for the CIM are on order.

Rose Bandrowski
Rose Bandrowski12:32 PM

Okay, are we looking at a normal Andymark CIM that we already have in stock? And do you think that's going to take a gearbox and if so have we speced one out and do we need to order one?

Rose Bandrowski
Rose Bandrowski12:33 PM

I'm not sure if that actually falls under scissor lift's to-do or my group's to do. They're integrated

Paul Vibrans
Paul Vibrans1:01 PM

The screw has direct drive without any gears. I don't know which group will own it.

Riyadth Al-Kazily
Riyadth Al-Kazily10:03 PM

I want to start a conversation about how the software team needs to control the intake grabber. Right now I don't know how many actuators (motors, pneumatic solenoids, servos) are being used, and what they do. Also, we need to communicate the sensors needed in order to perform operations. Are motors being run with precise speed control (meaning there are encoders attached to them)? Are there limit switches that we need to sense in order to turn off motors before we burn them out?
Basically I'd like to know all the states the intake grabber can be in, what motors are running while in those states, and what actuators do work in order for the physical state to change.

Chris Rininger
Chris Rininger10:04 PM

@Chris Rininger has joined the channel

Chris Rininger
Chris Rininger10:09 PM

Saw this grabber here just released by West Coast Products - sharing not because we'd buy it but because it's an interesting design & there might be some ideas from it worth borrowing - it's below the elevator. https://www.chiefdelphi.com/forums/showthread.php?threadid=161646

2018-01-20
Rose Bandrowski
Rose Bandrowski9:42 AM

Here's a list of updates from yesterday: We had designed the grabber arm with a different cube from the actual FIRST one, we need to make some adjustments for this
-Longer grabber arms
-Alignment with the handles (this will take thought on what angle or placement of the grabbers will get us that)
-10" pneumatic (we used 8")
-Grabber arm CAD is done?
-We need to finish the harvester ideas and finalize in cad

Rose Bandrowski
Rose Bandrowski9:44 AM

-need to look for hallow blue tubing on mcmaster(?)

Will Hobbs
Will Hobbs9:47 AM

Rose I thought we said we wanted a 9in

Rose Bandrowski
Rose Bandrowski9:47 AM

I thought it was 10?

Will Hobbs
Will Hobbs9:47 AM

I’m pretty sure the 10 in was to big

Will Hobbs
Will Hobbs9:47 AM

Whatever you need please let peter know

Rose Bandrowski
Rose Bandrowski9:47 AM

Yes but we can design the grabber attachments so it's not too big

Rose Bandrowski
Rose Bandrowski9:47 AM

I think that's what we concluded

Rose Bandrowski
Rose Bandrowski9:47 AM

I will

Will Hobbs
Will Hobbs9:48 AM

After the meeting we talked about what pneumatics to order and I told him to order more of the 8 in and a 9in

Will Hobbs
Will Hobbs9:48 AM

I think you decided against the 9in because we didn’t have one

Rose Bandrowski
Rose Bandrowski9:49 AM

Yeah and 10 is slightly too big but we decided we could work around that

Will Hobbs
Will Hobbs9:49 AM

Please confirm and let peter know before he places the order

Rose Bandrowski
Rose Bandrowski9:49 AM

Okay, when is he placing the order?

Rose Bandrowski
Rose Bandrowski9:50 AM

@brian_bonifaci @Julian Bonifaci I thought we decided on the 10" pneumatic?

Will Hobbs
Will Hobbs9:50 AM

I don’t remember off the top of my head. We placed an order using the voucher last night and I’m pretty sure they are placing another order Sunday

Rose Bandrowski
Rose Bandrowski9:51 AM

Okay. I'll see about confirming that

brian_bonifaci
brian_bonifaci9:51 AM

We planned on using the 10" we already have.

Rose Bandrowski
Rose Bandrowski9:52 AM

Okay that's what I thought

Will Hobbs
Will Hobbs9:52 AM

If that’s the plan we will probably need to order more

brian_bonifaci
brian_bonifaci9:52 AM

We have two.

Rose Bandrowski
Rose Bandrowski9:52 AM

Okay I can email peter to order... how many more do you think?

Will Hobbs
Will Hobbs9:53 AM

We want at least three of the same. 1 for the primary robot 1 for the secondary robot and 1 as a spare

Will Hobbs
Will Hobbs9:53 AM

If we have 2 than you only need 1

brian_bonifaci
brian_bonifaci9:53 AM

We may have 3 but I'm not sure.

Rose Bandrowski
Rose Bandrowski9:54 AM

also @Mark Tarlton we didn't finalize plans on the harvester how it'll retract and extend with pneumatics, but we're placing an order so do you have an idea on what sizes we're going to want?

Rose Bandrowski
Rose Bandrowski9:55 AM

We're working around having to rotate the harvester so it fits in the frame perimeter and we were discussing a design powered by pneumatics

Rose Bandrowski
Rose Bandrowski9:55 AM

that hasn't been tested or thought through though so I'm not sure what to tell peter or order

brian_bonifaci
brian_bonifaci9:55 AM

I saw someone entering an inventory of cylinders into a google doc.

Will Hobbs
Will Hobbs9:56 AM

Based on our pneumatics inventory we only have 2 10in pneumatics

Will Hobbs
Will Hobbs9:56 AM

This is the inventory sheet for this year

Will Hobbs
Will Hobbs9:56 AM

Pneumatics are on the last page

Rose Bandrowski
Rose Bandrowski9:57 AM

Brian, any thoughts on the size pneumatic we'd use for that harvester system?

Rose Bandrowski
Rose Bandrowski9:58 AM

If peters putting in an order I should tell him to order something so it gets here even if we're not sure

Will Hobbs
Will Hobbs9:59 AM

You want to order he 04 bore

Will Hobbs
Will Hobbs10:00 AM

Peter will know what that means

Rose Bandrowski
Rose Bandrowski10:00 AM

Okay

Rose Bandrowski
Rose Bandrowski10:00 AM

only one?

Will Hobbs
Will Hobbs10:00 AM

For the 10in

Will Hobbs
Will Hobbs10:00 AM

I don’t know if you want to order other sizes

Rose Bandrowski
Rose Bandrowski10:02 AM

So I'm assuming if we're going to be ordering a total of 4 10" pneumatics, you're going to want equal number of the 04 bore or am I assuming incorrectly.

brian_bonifaci
brian_bonifaci10:02 AM

Not sure. Short, around 4" maybe

Will Hobbs
Will Hobbs10:02 AM

Why 4 pneumatics?

Will Hobbs
Will Hobbs10:03 AM

You only need a total of 3 and you already have 2

Rose Bandrowski
Rose Bandrowski10:03 AM

Oh I misunderstood

Rose Bandrowski
Rose Bandrowski10:04 AM

Okay one ten inch pneumatic and a 04 bore

Rose Bandrowski
Rose Bandrowski10:04 AM

We have one 5" pneumatic, Brain

Rose Bandrowski
Rose Bandrowski10:05 AM

For that we're going to need one pneumatic per side (probably?) so we'd need two of the same size

brian_bonifaci
brian_bonifaci10:06 AM

Or 4 total for two robots.

Rose Bandrowski
Rose Bandrowski10:06 AM

plus one for a spare

brian_bonifaci
brian_bonifaci10:07 AM

Do we have enough air tanks, might need more reserve with all this.

Will Hobbs
Will Hobbs10:08 AM

They are ordering more tanks

Rose Bandrowski
Rose Bandrowski10:08 AM

Okay good

Rose Bandrowski
Rose Bandrowski10:10 AM

I'm going to wait and see if Mark has any input on the harvester pneumatic before I send that order.

Enrique Chee
Enrique Chee10:13 AM

Make sure @Peter Hall follows through with this order request ASAP. Air tanks and pneumatics cylinders.

Rose Bandrowski
Rose Bandrowski10:14 AM

Okay. Should I send him a request for 4 more 5" pneumatics? i'm unsure that's the one we want to use so I'm hesitant to request it

Enrique Chee
Enrique Chee10:22 AM

Please confirm all orders on Sun.

Rose Bandrowski
Rose Bandrowski10:22 AM

okay

Mark Tarlton
Mark Tarlton12:50 PM

What supplier do we use for pneumatic rams? I looked at Andymark and don't see 10" stroke so I assume we're getting them elsewhere. I

Will Hobbs
Will Hobbs12:51 PM

We buy them from bimba

Mark Tarlton
Mark Tarlton4:30 PM

@Rose Bandrowski.. I think we will need a 6" stroke to lift the harvester. I wouldn't want to go shorter.

Rose Bandrowski
Rose Bandrowski4:31 PM

Okay we'll confirm tomorrow

2018-01-21
Rose Bandrowski
Rose Bandrowski7:17 PM

It looks like the 10:1 gear box kit from Vex pro is out of stock, we already have enough for the first and second robot though so I'm going to call off the order for now

Will Hobbs
Will Hobbs7:21 PM

Place the order so we have spares

Rose Bandrowski
Rose Bandrowski7:23 PM

Okay

2018-01-22
Rose Bandrowski
Rose Bandrowski8:26 AM

I like the intake we've decided on but I found this cool design on chief delphi and I thought I'd dump it here for fun https://www.chiefdelphi.com/media/photos/45700?

Will Hobbs
Will Hobbs7:58 PM

Anybody have a picture of the prototype grabber

2018-01-23
brian_bonifaci
brian_bonifaci6:10 PM

2018-01-24
Micah C. Glasby
Micah C. Glasby5:29 PM

I drew up a possible design for the part of the arm in the robot. Given that we have only have 4 1/2 inches we wouldn't have a lot of room, but it saves us the hassle of trying to put the pulley in the arm itself.

2018-01-26
Chris Mentzer
Chris Mentzer12:31 PM

@Chris Mentzer has joined the channel

Robert Galvin
Robert Galvin8:13 PM

Sketch for cad

2018-01-29
Chris Rininger
Chris Rininger8:34 AM

Interesting insight from team 3847 that having more grab on one side of the intake than the other helps with acquiring cubes that are not squared up relative to the robot... https://www.chiefdelphi.com/forums/showthread.php?threadid=162013

Rose Bandrowski
Rose Bandrowski8:35 AM

I don't like putting different designs out there this late into the season, but this is really cool https://youtu.be/d-l09rh7EL0

Chris Rininger
Chris Rininger11:38 AM

Question regarding our Switch game: Are we dropping/placing (which requires contact with the fence around the switch) or are we launching using the flipper arm (which just requires being in the right zones)? Relevant conversation: https://www.chiefdelphi.com/forums/showthread.php?threadid=162017

Riyadth Al-Kazily
Riyadth Al-Kazily12:11 PM

We are not likely to be launching (flinging?) with the flipper arm, as the mechanism timing (motor and pneumatics) will be hard to synchronize without a great deal of programming effort.

brian_bonifaci
brian_bonifaci7:53 PM

Rose: I saw that design and I think it showed the importance of being able to pull a cube away from the wall and 'gather it' in one motion, which I think we can do if we refine our design.

Rose Bandrowski
Rose Bandrowski7:53 PM

Sounds good

2018-02-05
Robert Galvin
Robert Galvin1:40 PM

I'm going to be there about 10 minutes late today, I'll be there as fast as I can

Paul Vibrans
Paul Vibrans7:03 PM

Is there a CAD drawing for the pulleys being used for the intake?

Will Hobbs
Will Hobbs7:25 PM

Let me know if his doesn’t work and I can send a different link

Dana Batali
Dana Batali9:36 PM

2018-02-06
Micah C. Glasby
Micah C. Glasby6:19 PM

I'll be about an hour late, but I'll get there as fast as I can.

2018-02-08
Mark Tarlton
Mark Tarlton6:48 PM

In the programming thread, Dana thinks that the IR Sensor that Randy Groves has been working with will be able to sense the presence of a cube and can replace the switch we had planned on.

Mark Tarlton
Mark Tarlton6:58 PM

I have a version of the complete intake arms and mounts in CAD. I'll attach some screen shots showing how it fits in the robot

Mark Tarlton
Mark Tarlton6:59 PM

Mark Tarlton
Mark Tarlton6:59 PM

Mark Tarlton
Mark Tarlton6:59 PM

Mark Tarlton
Mark Tarlton6:59 PM

Kenneth Wiersema
Kenneth Wiersema7:50 PM

Thank you, I’ll see about transfering it to the main file. This sort of helps one of my problems

Enrique Chee
Enrique Chee8:30 PM

Do we have room for larger diameter confirming green wheels ?

Paul Vibrans
Paul Vibrans9:24 PM

Some of the stuff in the background is very wrong. What CAD background is being used?

Mark Tarlton
Mark Tarlton9:26 PM

it's very tight. There will be trade-offs to go larger and still fit.

2018-02-09
Mark Tarlton
Mark Tarlton2:52 PM

I took a closer look at using larger wheels on the intake arms. We would need to make the arms longer so that it would fold inside the chassis. Longer arms may interfere with the "Climb with friends" stabilizers.

Mark Tarlton
Mark Tarlton2:54 PM

The images were based on the "New Final Robot ..." model as it was yesterday afternoon.

Enrique Chee
Enrique Chee3:55 PM

If you feel confident that the smaller wheels are effective then no need for larger wheel.

Chris Rininger
Chris Rininger5:33 PM

I recommend prioritizing optimizing the cycle time of the harvest/grab/aim/place sequence above "Climb with friends", which seems very likely to be a casualty of limited remaining time. If fast harvesting requires longer arms, bigger wheels, etc. then go for it because switch/scale cycling is our top priority. If we DO get to CwF, I think we will find a way (use space above harvester possibly). Please do enable the arms to fold in at climbing time so they don't interfere.

2018-02-12
Rose Bandrowski
Rose Bandrowski8:55 AM

2018-02-16
Robert Galvin
Robert Galvin10:31 PM

I will not be there tomorrow. It would be great if tomorrow the pneumatic cylinder could be attached to the second harvester. After that we need to test the second harvester, make sure everything works, and attach to robot. Holes are already drilled on the robot, the harvester just needs to be bolted on. Other than that, before bag day all we really need to do is make spare parts, which shouldn't take too long. Let me know if I'm missing anything, otherwise I'll see you all on Sunday.

2018-02-17
Mark Tarlton
Mark Tarlton5:15 PM

The second intake was completed and tested today. Paul added lightening holes on both arms overnight so it's looking pretty good. Also Brian added a needle valve flow-restrictor to the main robot with flow set at 3.5 turns from fully closed -- it works really nicely!

Mark Tarlton
Mark Tarlton5:19 PM

We need to put together a list of spare parts. Off the top of my head, we need: a 7" pneumatic cylinder, more of the green conforming wheels, some 1/2" hex spacers (particularly the small ones for use on the wheel end of the arms. small 1/2" hex collars. We also need to make sure we have spares for all the various sizes nuts and bolts.

Mark Tarlton
Mark Tarlton5:20 PM

We need to take the extra gearbox/shaft components in case we loose the circle clips or locking screws. We also need to document the spacing and layout of the various components when assembling the complete unit. The spacing is particularly critical and is hard to recreate under pressure.

Mark Tarlton
Mark Tarlton5:28 PM

I think we could consider replacing the "churro" shafts with solid hex aluminum shafts -- particularly at the motor -- to tighten the assembly up. Also on the second robot, we're experimenting with putting the green wheel on the lower side of the upper arm to get a better grip on cubes. Finally, first chance we get, we should try to swap the intake assemblies on the main robot so that we're sure they are interchangeable and to put the lighter weight parts on the main robot.

Mark Tarlton
Mark Tarlton5:37 PM

We also want to think about adding a limit switch that indicates when the arms are closed. The programming team could use this to make sure the intake motors aren't running when the arms are closed.

Chris Rininger
Chris Rininger7:39 PM

Probably a crazy thought... there's no way to make the harvester rotate back once it's holding a cube in order to shoot into the switch is there? I noticed how nicely it pulls cubes in and then shoots them forward when motors are reversed - had to ask, because that would surely be a fast way to cycle on the switch

Will Hobbs
Will Hobbs7:40 PM

That would not be possible with the space we have available

Chris Rininger
Chris Rininger7:43 PM

even with it as it is, we should be fairly fast at cycling to the exchange at least

Mark Tarlton
Mark Tarlton7:50 PM

FYI -- I won't be in tomorrow -- family event.

2018-02-20
Enrique Chee
Enrique Chee10:14 AM

Students, Do we have a spare air cylinder for the harvester and grabber ? If not ,give me the specs to order.

Robert Galvin
Robert Galvin10:28 AM

We do not have a spare cylinder for the harvester. We need one that is 7" long. I believe the diameter is 3/4" but I want to double check that before anything gets ordered.

Robert Galvin
Robert Galvin11:01 AM

Yeah it's 3/4"

Robert Galvin
Robert Galvin11:01 AM

But jack should have already placed the order

Mark Tarlton
Mark Tarlton11:12 AM

7" x 3/4" is correct. I set down with Jack yesterday to verify the specs. I asked him to order a pair.

2018-02-25
Micah C. Glasby
Micah C. Glasby9:34 PM

Track starts tomorrow so I can't make it to the meeting

2018-03-05
Rose Bandrowski
Rose Bandrowski10:55 AM

Thinking about a new harvester design. This whole thing is so complex, but if we want to be a more competitive robot this is the most sensible way to improve. I have no idea if we actually have space next to the lift to mount a pneumatic or motor, but if we did, this is my idea. Just an idea

2018-03-06
Ethan Rininger
Ethan Rininger10:41 AM

How heavy is the current grabber and intake system together

Mark Tarlton
Mark Tarlton10:50 AM

I don't know. We didn't weigh them when they were off.

Mark Tarlton
Mark Tarlton11:13 AM

I'd guess around 7lbs for intake system with 1/3 of that weight being motors and gearboxes. I'd also guess around 3 lbs for grabber.

Paul Vibrans
Paul Vibrans9:08 PM

I have a good start on a combined harvester/grabber design. The motor will be close to the flipper hinge. I hope for a CAD image tomorrow evening.

Paul Vibrans
Paul Vibrans9:09 PM

There is also a camera mount concept for the top of the scissor lift.

Kaedric Holt
Kaedric Holt11:10 PM

Thanks Paul.

2018-03-07
Enrique Chee
Enrique Chee7:22 AM

@Paul Vibrans some of the mechanics will be in the robot room from 3:15 till 5 pm on 3/7 and 3/8.

Mark Tarlton
Mark Tarlton10:31 AM

@Paul Vibrans where did you say you found a plastic hex shaft? All I found on Vex / West Coast / Andymark was ThunderHex (7075 -T6). On other sites I found Nylon hex and other weaker plastics.

Paul Vibrans
Paul Vibrans11:57 AM

I did not find plastic hex shaft. I found plastic 1x2x0.1 rectangular polycarbonate tube at VEX

Paul Vibrans
Paul Vibrans12:00 PM

7075-T6 aluminum is stronger than ordinary steel, less ductile, not as stiff and 1/3 the weight.

Enrique Chee
Enrique Chee12:46 PM

Do you want me to order ? Exact item # ? @Paul Vibrans

Harrison
Harrison12:58 PM

@Harrison has joined the channel

2018-03-08
Riyadth Al-Kazily
Riyadth Al-Kazily10:24 AM

Regarding potential design changes to the harvester (as indicated in James S. email to the mentors), I would appreciate it if the team could post some sketches to show how the device will be actuated, pointing out how it differs from the original design.
What caught my eye was "replacing the pneumatic with a pulley belt system and a spring..." That implies changes to plumbing, wiring, and programming. The earlier we can review and comment on this plan, the more likely we can all arrive at success at the same time.

Mark Tarlton
Mark Tarlton10:45 AM

I hope to have a proposed design together today. I'm working through the details of the various options now. In the minimum, no changes to the control will be needed but we won't be able to change intake wheel size. If we go to the belt system, we might need to add one more pneumatic cylinder and the control sequence would change as well. If we go this route, we may be able to try larger wheels, place the arms below the grabber and explore other configuration options. For sure, we are staying with pneumatics and the same general components.

Kenneth Wiersema
Kenneth Wiersema10:49 AM

Not necessarily, I thought we would still have one pneumatic, that has the belts connected with it. The set up is still relatively unchanged. The hope with electronics is that the setup is unchanged. We will not be adding a more controller.

Mark Tarlton
Mark Tarlton10:08 PM

The big changes for the harvester is where the arms start at the beginning of the match and how pneumatics drive the position of the arms. The idea is to have the arms point towards the back of the robot when the event starts, swing towards the front to get into grabbing position and then swing the rest of the way in to grab cubes. By starting in back, we aren't as space constrained as we are now. Larger wheels can be used and we will have more flexibility in how the arms are positioned.

The biggest change in the hardware is with the pneumatics that control the arm positions. They need to change to support the extended range of motion (up to 270 degrees of rotation) and three stopping positions instead of two. We'll need to add a second pneumatic cylinder and solenoid. The way it would work is that springs pull the arm so that its pointing straight back. When one pneumatic is activated, it will pull 1/2 of the belt which rotates the arm about 130 degrees . This is about the same position that we use now for the "arm open" position. When the 2nd pneumatic is activated, the arm rotates another 130 degrees. If a cube is in position, it will grab the cube. If no cube is there, then it will rotate towards the front of the robot but probably won't close completely. The linkage between the belts and the pneumatics is such that if only one arm hits the cube, the other arm will remain open as well.
Moving the pneumatics will fix the problem where the arms get caught in the closed position. It will also fix the problem where one arm closes by itself when the cube is off center.
Larger wheels in front will give better grip on the cubes and will act as a bumper when the arms run into things.
We'll also have flexibility in setting the height of the arms. We might be able to set them low enough that the grabber can be used while the arms are holding the cube.

2018-03-09
Paul Vibrans
Paul Vibrans6:21 AM

We have enough materials on hand to make one Combined Harvester Grabber except for the following items: 2 each VEX 217-3463, 2 each VEX 3460, 13 each VEX 217-2737, and 16 each VEX 217-3875.

Paul Vibrans
Paul Vibrans6:43 AM

If we build a second Combined Harvester Grabber, we need to acquire the following additional items: 2 each VEX 217-4100, 8 each VEX 3432, 2 each VEX 217-3200, 6 each VEX 217-4009, 4 each VEX 217-3199, 1 each VEX 217-4973, 1 each VEX 217-2818, 2 each VEX 217-2816, 2 each VEX 217-3463, 2 each VEX 217-3460, 16 each VEX 217-2737, 16 each VEX 217-3875, 3 each WCP 0097, 4 each WCP 0096, and 4 each generic 1603-ZZ.

Enrique Chee
Enrique Chee7:30 AM

@Kaedric Holt or @Jack Chapman please put items in vex cart so we can purchase if we decide this route .

Paul Vibrans
Paul Vibrans12:15 PM

There will not be enough time between Glacier Peak and Portland to build and test a Harvester Grabber, let alone building one for the competition robot. Also I will be traveling for 4 of the days in that period and will not be much help with construction.

Kaedric Holt
Kaedric Holt2:01 PM

I will get everything in the cart as soon as I have access to a computer.

Enrique Chee
Enrique Chee2:45 PM

@Paul Vibrans Not clear. Are we building a combined harvester ? or not ?

Paul Vibrans
Paul Vibrans2:55 PM

I can't make that decision. If a revised harvester and the existing grabber work well enough to win in Portland as determined by our Glacier Peak performance then we won't need a Harvester Grabber. If they don't work then we need a Harvester Grabber ready to test the day we get back from Glacier Peak.

Kenneth Wiersema
Kenneth Wiersema2:56 PM

Not right now, possibly later as a back up plan, if we need something better from glacier peak

Mark Tarlton
Mark Tarlton3:07 PM

I think the question Paul raises is whether we want to have a solution in our pocket before the need actually arises or do we bet everything on what we're doing now. It's a risk/reward question for the team.

Mark Tarlton
Mark Tarlton3:10 PM

There is a cost (time, materials, and team attention) in creating the integrated H/G solution. On the other hand, if we find we do want it, the development lead time is such that we have to start now.

Kaedric Holt
Kaedric Holt4:01 PM

The 4 single polycord pulleys from WCP are backordered.

Paul Vibrans
Paul Vibrans4:08 PM

Substitute double groove pulleys.

Kenneth Wiersema
Kenneth Wiersema4:11 PM

What else do we need gearbox wise? I know about the extra ring gear needed, and I got spares for the two harvester motors, and one for the main climber motor, but is there anything else?

Paul Vibrans
Paul Vibrans4:17 PM

We have everything we need for the first one except 4 belts, 13 collars and 16 bearings. They are on the first shopping list from this morning. The second shopping list is for the second robot and is in addition to the first shopping list. The second shopping list replaces what we took out of inventory on Thursday.

Kenneth Wiersema
Kenneth Wiersema5:02 PM

Okay good to know, thank you

2018-03-10
Chris Rininger
Chris Rininger7:44 AM

Is the combined design posted somewhere?

Chris Rininger
Chris Rininger7:49 AM

One observation from watching fast cycling teams is the ability to softly “shoot” the cube a few feet helps a lot with cycling fast and not getting hung up on the scale, so I would hope any complete redesign we do has that requirement on the list.

Mark Tarlton
Mark Tarlton9:01 AM

@Paul Vibrans @Enrique Chee I didn't see an order for the polycarbonate box beams. Do we still want to get that?

Enrique Chee
Enrique Chee9:06 AM

I did not get that order. @Mark Tarlton FYI. Students are available on Mon around 3 pm and Tues after 3:10 pm.

Mark Tarlton
Mark Tarlton9:07 AM

Thanks. I will be there.

Mark Tarlton
Mark Tarlton9:32 AM

The new harvester will use aluminum. I thought Paul was considering the plastic tubing for his design. We saw it being used on another team's integrated grabber that's very similar to Paul's design.

Paul Vibrans
Paul Vibrans10:20 PM

The cross structure is aluminum. We have aluminum in inventory for grabber arms though polycarbonate 1x2 tubing is preferred. It is VEX 217-4819. I think we can survive without it at this time.

2018-03-11
Paul Vibrans
Paul Vibrans8:55 PM

We need to replenish our stock of 1"x 1-1/2"x 1/8" rectangular aluminum 6061-T6 tube.

2018-03-12
Enrique Chee
Enrique Chee9:13 AM

Ok, will order more.

2018-03-13
Chris Rininger
Chris Rininger7:32 PM

decent looking polycarb intake - ideas to borrow possibly: https://www.youtube.com/watch?v=PqV7966H8aQ&feature=youtu.be

2018-03-15
Paul Vibrans
Paul Vibrans7:58 AM

Two stalks, two arms and one crossbar need to be made for the Harvester/Grabber. Drawings are attached.

Paul Vibrans
Paul Vibrans7:58 AM

Paul Vibrans
Paul Vibrans7:58 AM

Paul Vibrans
Paul Vibrans8:14 AM

The Harvester-Grabber assembly is shown, minus the air cylinder, belts, and spring.

Chris Rininger
Chris Rininger8:37 AM

Any chance these would work on the front? Jack in the Bot folks said they tested lots of compliant wheels & these worked best on the front of their intake. http://www.andymark.com/product-p/am-0619a.htm

Justice James
Justice James10:41 AM

This is a close-up of Team 2910's intake system, for anyone interested.

Chris Rininger
Chris Rininger3:13 PM

“Best intakes” thread on Chief Delphi: https://www.chiefdelphi.com/forums/showthread.php?threadid=163910

Mark Tarlton
Mark Tarlton6:42 PM

They should work better than what we planned. They have 1/2" hex shaft but they're 1/2" high compared to the 1" height of the big green wheels. This would allow us to space the arms closer together.

Mark Tarlton
Mark Tarlton6:48 PM

Regarding the height difference, I just noticed in the photo posted, that they are using two wheels stacked one on top of the other so it's back to 1" total thickness. That would be another option to try. The spikes might also reduce the change of arms getting wedged together

2018-03-16
Jack Chapman
Jack Chapman4:18 PM

Tell me if the link doesn't work, I've been having issue

Justice James
Justice James4:19 PM

It works

Rose Bandrowski
Rose Bandrowski5:58 PM

I wish I had more energy to keep up with the new intake. That looks cool! How effective is it? I’m assuming since the wheels are larger it flips up now?

Will Hobbs
Will Hobbs6:06 PM

It rotates so the arms face the back of the robot at the beginning of the match

Rose Bandrowski
Rose Bandrowski6:07 PM

Nice

Chris Rininger
Chris Rininger7:15 PM

Has there been a discussion with programming yet?

Justice James
Justice James7:16 PM

@Ryan Olney

2018-03-17
Ryan Olney
Ryan Olney7:30 AM

@Ryan Olney has joined the channel

Declan Freeman-Gleason
Declan Freeman-Gleason10:23 AM

There has not been a discussion with programming, as far as I'm aware (If someone talked about this while I was gone, please post a message filling us in.)

We need an overview of the different states that the harvester needs to get into, and roughly how they get there. This can come from someone who has a good understanding of the whole design. This is the most important thing you can answer.

We also need an electrical overview, probably from @Peter Hall. How is this wired, what new solenoids are there?

Peter Hall
Peter Hall10:46 AM

Currently the plan is to have two separately actuated cylinders. For the intake we will have two solenoids each controlling one cylinder. The solenoid ID's are 5 and 6.

Peter Hall
Peter Hall10:47 AM

One of the cylinders is longer than the other. So we will have to work on which is moved and when.

Will Hobbs
Will Hobbs10:48 AM

@Mark Tarlton will have the best answer for you

Declan Freeman-Gleason
Declan Freeman-Gleason10:49 AM

Without feedback you're not going to get those moving in unison. We could use a hall effect sensor to tell when we should begin to actuate the shorter one.

Enrique Chee
Enrique Chee11:27 AM

FYI, @Mark Tarlton Some of us are meeting on Sun. 3/18 from 12 to 5 pm to finish new harvester.

Mark Tarlton
Mark Tarlton11:29 AM

@Declan Freeman-Gleason: here's the first part. poke me if it's not clear or you need more info

Mark Tarlton
Mark Tarlton11:29 AM

The big changes for the harvester is where the arms start at the beginning of the match and how pneumatics drive the position of the arms. The idea is to have the arms point towards the back of the robot when the event starts and then swing towards the front to get into grabbing position and then swing the rest of the way in to grab cubes. The new mechanical design has the arms always moving in complement -- opposite direction but rotated the same amount. If only one arm engages the cube, the other arm will not rotate in and block intake as the old design did.

To do this we added a second pneumatic actuator. The two cylinders' motions are added together to rotate the arms but since they are of different lengths, it's important to know which one is which. For now, let's assume P1 is the longer cylinder (an 8" cylinder) and that it's attached to the existing solenoid used by the harvester. P2 is the shorter cylinder (5") that's attached to a new solenoid that the Pneumatics team needs to install. Assuming there's nothing blocking the arm rotation, this configuration gives us four rotation positions. One of the partially open positions isn't particularly useful and if a cube :
P1 P2 Arm angle Description State Name
0 0 0 Arms pointing straight back FULL OPEN
0 1 103 degrees Arms pointing out to the sides NOT USED
1 0 166 degrees Arms forward and slightly open. PARTIALLY CLOSED
1 1 185 degrees Arms trying to close but cube being held CUBE HELD
1 1 270 Arms folded in front FULL CLOSED
I don't see much value in the 103 degree position so I'm ignoring it for now


The states then are:
• "FULL OPEN" : the arms are all the way back alongside the lift. This is the starting position. Let's call this 0 degrees.
• "PARTIALLY CLOSED" : the arms are partially forward. This is the common position when trying to grab a cube. This is the case when one of the two pneumatics are closed. In theory, there can be two different positions for "PARTIALLY CLOSED" but I expect that one of the positions will not be exposed by the programmers to simplify driver control.
• "CUBE HELD" : the arms are approximately straight forward. This is the common position when holding a cube. Both pneumatic cylinders are powered in the close state but the cube is preventing full closure.
"FULL CLOSED" : the arms are folded in front of the robot. Both pneumatics are in the full closed state. This can happen if the arms fail to grab a cube or if the driver chooses to close the arm without a cube. Depending on how the arm heights are configured, full closed may only be to the point where the arms hit each other along the centerline of the robot. This position may be useful for knocking cubes out of the pile.

Enrique Chee
Enrique Chee11:30 AM

Thank you @Mark Tarlton

Will Hobbs
Will Hobbs11:32 AM

@Mark Tarlton I thought her we were using a 7in and a 5 in. Not a 8in and 5 in

Will Hobbs
Will Hobbs11:32 AM

If I am wrong this is a pretty easy fix

Mark Tarlton
Mark Tarlton11:33 AM

7 and 5 was the original plan but reuse of the pulleys changed the numbers.

Kenneth Wiersema
Kenneth Wiersema11:35 AM

Things are starting to get a little tight on the robot with the increasingly large pneumatics. Also I don’t know how much space we need for the entire cable set up, but things will be very tight now

Declan Freeman-Gleason
Declan Freeman-Gleason11:36 AM

Thanks @Mark Tarlton! The pnuematics are connected to each other then? Does that mean that the system will make itself go to those angles as a result of the solenoid states that you have in the table? (I'm assuming that the numbers under P1 and P2 are solenoid states, correct me if I'm wrong.)

Mark Tarlton
Mark Tarlton11:37 AM

actually the 7 does work better but the numbers I gave will change slightly. It won't close fully, but the intermediate positions are better with 7"

Will Hobbs
Will Hobbs11:37 AM

That would actually be ideal

Enrique Chee
Enrique Chee11:37 AM

Do we have 8 inches ? I just ordered from AM four 7 inches.

Kenneth Wiersema
Kenneth Wiersema11:38 AM

We have 8 in pneumatics, I remember that we were distinctly missing 7in, but we were finding a lot of 8”.

Will Hobbs
Will Hobbs11:39 AM

Based on how we set up the arms they can not close fully without some changes

Will Hobbs
Will Hobbs11:39 AM

The 7in pneumatics should be better

Will Hobbs
Will Hobbs11:39 AM

And we did find 3 7in pneumatics

Mark Tarlton
Mark Tarlton11:39 AM

We had 8" laying around which is why I proposed that number. If 7's are in that's the way to go.

Kenneth Wiersema
Kenneth Wiersema11:40 AM

I thought we only had two 7”, not counting the one on the 1st robot, and one with a bent shaft.

Will Hobbs
Will Hobbs11:40 AM

We used 7 in pneumatics in the first harvester

Will Hobbs
Will Hobbs11:41 AM

So we have 1 on each robot and 1 spare

Will Hobbs
Will Hobbs11:41 AM

And Mr. Chee ordered more

Mark Tarlton
Mark Tarlton11:45 AM

with 7" and 5" cylinders the angles are: 0 degrees (straight back), 104 (not used), 145 degrees, and 250 degrees (crossed but not completely folded in front). We should fold the arms back when climbing in this configuration to avoid compressing the arms against the tower.

Enrique Chee
Enrique Chee11:45 AM

I just ordered four 7 inches that won't get here till the end of the week.

Mark Tarlton
Mark Tarlton11:46 AM

We just need one 7" per robot so reusing what's already installed will work

Mark Tarlton
Mark Tarlton11:47 AM

we do have two 5" so no spares at this moment.

Mark Tarlton
Mark Tarlton11:50 AM

Also, in Jack's video it looked like cubes were getting hung up on the middle wheel. It could be that we just need to run the motors faster. If they're still a problem, I'd suggest trying larger diameter wheels there to see if that eases the transition.

Chris Rininger
Chris Rininger12:46 PM

I saw the eject is stronger & the arms rotate up... possible to shoot into switch now rather than use the 2-stage place? If so, is there a positional state needed for that?

Mark Tarlton
Mark Tarlton1:00 PM

There may be ways of using the cable tension when grabbing a cube to tilt the arms back up. But it could be we have to lock the tilt in to make the rotation work at all. One thing I'd like to try is to see if the robot can harvest and grab a cube without coming to a stop.

Mark Tarlton
Mark Tarlton11:21 PM

Yes you got it right. The pneumatics are coupled together so that their actions kinda get added together. The table formatting got messed up but you're right ..
0. 0 0
0. 1. 103
1 0 166
1. 1. 185. (cube in arms)
1. 1. 270. ( No cube in arms)

I was in a rush, but I intended 0 to imply not actuated and. 1 to be actuated. You don't need to worry about the actual angles, just when to actuate each of the solonoids. Essentially P1 brings the arm from the back position to the ready position, and P2 closes the arms on the cube.

I won't know for sure if the grabber can grab while the harvester is holding the cube. We'll find out once it gets installed.

The motors should be off when arms are stowed in back and otherwise should behave as before.

2018-03-18
Declan Freeman-Gleason
Declan Freeman-Gleason9:35 AM

Great explanation! Thanks again. This looks like it's going to be pretty easy to get into our code. Must see for @Ronan Bennett @Darwin Clark

Declan Freeman-Gleason
Declan Freeman-Gleason12:31 PM

@Ryan Olney

James Sovick
James Sovick12:54 PM

@James Sovick has joined the channel

2018-03-19
Peter Hall
Peter Hall3:33 PM

@Paul Vibrans What is the length of the cylinder that is powering the integrated harvester grabber?

Cruz Strom
Cruz Strom4:12 PM

Cruz Strom
Cruz Strom4:12 PM

@Paul Vibrans

Rose Bandrowski
Rose Bandrowski4:13 PM

Whoa cool!

Paul Vibrans
Paul Vibrans4:13 PM

7, 8 or 9 inches. Whatever we have in inventory. I started working with a Bimba M-048-DP.

Will Hobbs
Will Hobbs4:18 PM

@Paul Vibrans how are the arms attached to the back brace

Peter Hall
Peter Hall4:19 PM

@Paul Vibrans Yes that size will work well we have 4 M-048-DP it would be great if we could stick with that size.

Paul Vibrans
Paul Vibrans4:28 PM

H-G arms are attached with hex shafts. There is an image of the assembly posted on March 15. It is not that great showing the detail. From the top down there is a double pulley (that could be a single), a tall spacer, the cross bar with bearings, a 15T cog belt pulley, and finally the grabber arm with bearings.

Will Hobbs
Will Hobbs4:30 PM

Sorry I meant the stalks

Will Hobbs
Will Hobbs4:31 PM

The arms are attached

Will Hobbs
Will Hobbs4:31 PM

How tall is a tall spacer?

Paul Vibrans
Paul Vibrans5:07 PM

1.09374 inches

Paul Vibrans
Paul Vibrans5:09 PM

Actually 1.09375 inches. Small keyboard and fat fingers.

Paul Vibrans
Paul Vibrans9:58 PM

There are two of these on the Harvester/Grabber. They need holes drilled to match the stalks once they are positioned. I have cut them out and will add the holes shown for pulley mounting.

Paul Vibrans
Paul Vibrans10:18 PM

Not shown are the posts to which the air cylinder connects. Also needs rubber band springs to squeeze the arms when the air is off. Needs a stronger counterbalance than is on the existing flipper because of the extra weight. Motor power comes from one of the existing harvester controllers. Air comes from the existing grabber solenoid valve(s) with the same logic. Motor logic is the same as the existing harvester when the new H/G is down. It is reversed when the new H/G is up and the cube is on its back.

Enrique Chee
Enrique Chee11:06 PM

Thanks Paul

2018-03-20
Paul Vibrans
Paul Vibrans9:29 AM

@Will Hobbs The pulley brackets that I dropped off this morning need to be trimmed with the band saw to match the drawing. Otherwise the vertical legs will interfere. You might get away with trimming just one but that means it only fits one location.

Will Hobbs
Will Hobbs9:40 AM

Ok

2018-03-21
Enrique Chee
Enrique Chee11:53 AM

@Mark Tarlton We also have a heating tool to fuse cords. Remind me to show you. I don't know why the team does not use that. We used it last year.

Mark Tarlton
Mark Tarlton12:33 PM

We did use it earlier in the year but the lighters were easier and faster.

Mark Tarlton
Mark Tarlton1:38 PM

@Paul Vibrans we're fighting the pulleys and risk not using the new harvester/grabber at GP. What do you think of going with two motors, one on each arm and getting rid of the pulleys and bands altogether?

Darwin Clark
Darwin Clark1:43 PM

@Mark Tarlton Is that the only mechanical issue we risk with the new harvester? Is weight a problem?

Paul Vibrans
Paul Vibrans1:44 PM

Weight may be a problem.

Paul Vibrans
Paul Vibrans1:45 PM

Can you flare the pulley grooves? They are pretty tight.

Mark Tarlton
Mark Tarlton1:48 PM

Belts seem to be a show stopper at this point. I'm not aware of other problems at this point but we haven't been to run long enough to know. We are also out of time. I think if we had another day we could probably sort out the pulleys but as it stands now, running the old harvester grabber is the default choice

Mark Tarlton
Mark Tarlton1:51 PM

To me, trying two motors and then going all out with counterbalance tubes has the highest chance of success in the time we have. We're also seeing a lot of wear in the double pulley mounted on the motor

Darwin Clark
Darwin Clark1:52 PM

Mark, when you say 'counterbalance tubes' what do you mean?

Mark Tarlton
Mark Tarlton1:58 PM

Elastic tubing that acts as a spring so that when the HG is rotated forward, the tubing stretches and helps lift it back. Like we already use to help the lift up and help grabber up

Paul Vibrans
Paul Vibrans2:22 PM

It takes 2 BAG motors and the trick is to keep everything compact.

Paul Vibrans
Paul Vibrans2:26 PM

We can slot the cross tube to the holes for the vertical shafts so we can slide the motor shafts, couplings and shortened vertical shafts in from the side using the same VEX bearing blocks. Angles for resisting motor torque will have to be added to the cross tube.

Will Hobbs
Will Hobbs2:43 PM

Harrison
Harrison3:16 PM

When we are moving the grabber are they going to be in the same positions.

Paul Vibrans
Paul Vibrans9:26 PM

Before giving up entirely on the revised harvester/grabber we should consider that not being able to eject is caused by lack of motor torque. Changing arm design will not improve this, especially if the outer wheels are 4 inch diameter as are the ones on the H/G that has been built. Can we change to VEX 775PRO motors on the same gearboxes? They weigh only 0.09 pounds more each than BAG motors and have about twice the torque at the same RPM. We also could extend the arms by using smaller drive pulleys on the outer wheels.

Harrison
Harrison9:30 PM

No that is not what I am worried about is if we go for the revised version of the grabber for competition. Should we also change the angle of where the grabber grabs the cube.

Harrison
Harrison9:34 PM

If that doesn't make sense then I can explain what I mean for the next meeting.

Paul Vibrans
Paul Vibrans9:35 PM

that isn't supposed to change

Harrison
Harrison9:36 PM

Oh ok

Harrison
Harrison9:37 PM

I was thinking since you can't really pick up a cube with the grabber facing downward.

Harrison
Harrison9:37 PM

Sort of like trying to cut vegetables by aimlessly stabbing

Paul Vibrans
Paul Vibrans9:44 PM

Did the old harvester with the BAG motors really eject cubes into the vault?

Harrison
Harrison9:46 PM

That I know of, the only time we did the vault we had a bit of a challenge ejecting the cube. But I believe we were still able to get 5 or 6 cubes in the vault.

2018-03-22
Paul Vibrans
Paul Vibrans8:19 AM

Before we scrap the new harvester/grabber in favor of old harvester arms added to the top of the scissor, we need to know why the old harvester worked and the new H/G does not.

Will Hobbs
Will Hobbs8:27 AM

Based on what I was seeing I think it has to do with the shorter arms

Will Hobbs
Will Hobbs8:28 AM

When you watched the new harvester attempt to grab cubes it would hit a corner or side and push the cube away rather than suck it in

Paul Vibrans
Paul Vibrans8:48 AM

My analysis is that part of the success of the old harvester was because the harvester attachment to the frame is below the line of action of the intake rollers such that the intake force tends lift the cube, reducing floor friction. This is true in both the intake and eject modes.

The line of action of the new H/G is well below the pivot at the end of the scissor lift. The intake and eject forces tend to rotate the cube into the ground, increasing friction like a self activating brake. The solution to this is to rotate the H/G down on intake so it has a significant lift function and then to rotate the H/G up on eject. Changing to old harvester arms will not change this.

Grabbing cubes off the wall may be a problem because there are only 2 positions for the H/G arm cylinder, open and grab. There needs to be a neutral position where only the spring (rubber tube) force clamps the arms together. This is how 4911's grabber works. 4911 told me they struggled to get just the right tension on their spring and they actually did not have a forced open position, just grab and neutral.

We can add a link easily to the new H/G arms that does not require pulleys and cables to make the arms work in direct opposition. Maximum open position may not be as wide as desired, but it will allow testing.

Large diameter rollers at the ends of the arms probably work against effective gathering because they will be more difficult to squeeze between cubes.

We have not done enough testing with what we have to know what is really going on with any of our systems.

Mark Tarlton
Mark Tarlton2:23 PM

My impression is that the arms and wheels were contacting the cube in front of the CG and so the cube spun away or was pushed back by the arm instead of being pulled in. Especially when the cube was twisted 45 degrees, the arms weren't getting behind corners of the cube. Cube placement had to be very close to square to get a grip on both sides to pull it in. I agree that the forward tilt of the old harvester arms helps lift the cubes some but I don't think that accounts for what we were seeing.

Paul Vibrans
Paul Vibrans4:02 PM

And the old harvester doesn't do the same thing when contacting cubes in the same place?

Paul Vibrans
Paul Vibrans4:05 PM

If that is true then there is an advantage for small diameter intake wheels, smaller than 4".

Chris Rininger
Chris Rininger4:39 PM

Seems like some iterative test with different options is needed.

Mark Tarlton
Mark Tarlton5:14 PM

If by "the same place" you mean the position of the cube relative to the robot, then the two arms give very different results. The V1 harvester arms will contact the cubes from the side while the HG arms will hit from the front and the cubes will bounce off. The HG arms need the cube to be very close to the target before they can be used effectively. Close enough that the old grabber could probably be used directly to grab the cube. This small working area of the HG intake is what motivated last night's discussion.

There V1 arm hinge also a mechanical stop that prevents the arms from being pushed to far open. That helps the arms guide the cube home. The distance between the two arm pivots is slightly larger than the cube width and was determined by the gap in the bumpers. I would have liked the pivots farther apart but the grabber /flipper needed the cube as close to the frame as we could get. Wider arm pivots would improve the contact angles between the wheels and the cube making the target volume even larger. The diameter of the wheels also factored into the pivot spacing. Since V2 harvester was using larger wheels, the pivot spacing was increased accordingly. A smaller internal wheel was added in the middle of the arm to guide the cube into the bumper gap. I didn't see the V2 arms run enough to get a sense of their performance relative to the V1 arms.

BTW, the use of belts along the length of the arms was an explicit request from the drive team at the beginning of the season. We added the small wheel simply to help get the cube moving in the right direction and keep them from hanging up on the front corner of the arm. That may still be a better choice.

Paul Vibrans
Paul Vibrans5:35 PM

I meant the position of the end of the arm and the center of gravity of the cube.

Paul Vibrans
Paul Vibrans5:36 PM

The issues of opening limits for the H/G have not been investigated fully because of time diverted by the belt drive.

Paul Vibrans
Paul Vibrans5:40 PM

We can easily add hollow polyurethane belting around the toothed belting to create a traction surface between the H/G wheels. It doesn't need to carry power, just be sticky.

Paul Vibrans
Paul Vibrans5:45 PM

The spacing of the V2 harvester pivots must allow the cube to be gripped securely when the robot gets bounced around. If it is going to be part of a grabber that is.

Mark Tarlton
Mark Tarlton5:53 PM

Ahh. By V2 harvester I was referring to the new version of harvester-only that we built. I used HG to mean the harvester/grabber.

I think constraining arm movement to both limit the amount the arms open and having them move in sync are important to performance. As you pointed out, the HG doesn't need a very wide range of motion so a simple linkage will suffice to keep them in sync.

2018-03-23
Enrique Chee
Enrique Chee12:23 PM

Vex 1x2 " polycarbonate is in

Enrique Chee
Enrique Chee12:24 PM

And star intake wheels

Enrique Chee
Enrique Chee12:50 PM

@Paul Vibrans @Mark Tarlton

2018-03-26
Paul Vibrans
Paul Vibrans6:43 AM

The H-G cylinder attachment needs to be moved so it can be made stronger. Drill a 0.25 hole through the arm where the cylinder needs to be attached. Drill out the 0.25 hole in the top to 0.5 so a half-inch rod with 1/4-20 tapped holes in each end can be pushed in and attached with a screw in the bottom. Attach the cylinder with screws in the tapped holes in the top.

Paul Vibrans
Paul Vibrans6:56 AM

Two solenoid valves are required, one to fill and vent the cap end of the cylinder to open the arms and one to fill and vent the rod end to close the arms. There are three arm conditions: forced apart, floating free, and forced together.

Add a means to keep the arms from opening too wide. Add a means to keep the arms from closing too much. Add a spring to close the arms when both ends of the cylinder are vented. Adjust the spring tension to grab cubes most effectively.

Mark Tarlton
Mark Tarlton7:09 PM

@Paul Vibrans.. good progress with the HG today. They removed the pneumatic cylinder and repositioned the elastic to make more room for the cube coming in. Now performing much better. Kenneth is working on the new pneumatics and linkage layout. The challenge with the linkage is to not block the cube when coming in. They're still working to get the lift counterbalance sorted. If they need to rebuild the arms or crossbar, should they use polycarb box or stick with Alum?

Paul Vibrans
Paul Vibrans7:29 PM

Polycarbonate, it is more shock absorbing.

Mark Tarlton
Mark Tarlton8:00 PM

Thanks! Lightening holes to reduce weight?

James Sovick
James Sovick8:06 PM

Yes

Will Hobbs
Will Hobbs8:17 PM

If you look in the grabber folder on fusion you can see my slightly edited version of the new design

Will Hobbs
Will Hobbs8:17 PM

I am not quite done but its almost there

Will Hobbs
Will Hobbs8:23 PM

2018-03-27
Paul Vibrans
Paul Vibrans4:42 AM

No lightening holes in polycarbonate

Chris Rininger
Chris Rininger9:03 AM

Consider leaving room for a centered low (but not too low) camera for assisting acquisition of cubes not in direct sight lines. With HG rotated down for cube acquisition, the proposed camera on the HG arm will be pointed down & unusable for this purpose. The HG cam will really then be for high placing. Not the top top priority I know, but good to keep in mind.

Paul Vibrans
Paul Vibrans12:18 PM

Behind the bar is ok if the hooks clear

2018-03-28
Violet Advani
Violet Advani1:26 PM

@Violet Advani has joined the channel

Enrique Chee
Enrique Chee8:58 PM

@Will Hobbs @James Sovick Did the new elastics work ?

Will Hobbs
Will Hobbs8:59 PM

We have not tried them yet

Will Hobbs
Will Hobbs8:59 PM

We were in the process of re stretching them when we left

Enrique Chee
Enrique Chee9:07 PM

Do you think the robot is ready for programmers by Friday afternoon ?

Enrique Chee
Enrique Chee9:07 PM

@Will Hobbs

Will Hobbs
Will Hobbs9:11 PM

I think it will be. But I don’t know how complicated the pneumatic mount will be

Mark Tarlton
Mark Tarlton10:00 PM

The pneumatics are almost finished. We probably won't get the arm linkage working, there's not enough space but it isn't essential and can be added later if we figure it out. For me, the big question is with scissor lift and elastics. Finding the right balance so that it can go up with a cube and come down empty may be tricky.

2018-03-30
Ronan Bennett
Ronan Bennett7:42 PM

@Ronan Bennett has joined the channel

Kenneth Wiersema
Kenneth Wiersema10:45 PM

As of today we’ve been working on this new variant of the harvester grabber for 5 days now, and a new harvester for the past 2 weeks. We have not had a single design that has been successful as of today, with issues continuing to plague us. This week we have been taking Paul’s design and modifying it with an end date of Friday to determine whether we will be using it or not at Portland.

On Thursday we got the pneumatic mounted and up and running. It looks promising with a quicker cube acquisition and securing system that seemed to be able to pick cubes up well. However we became plagued with the problem we still haven’t solved, the scissor lift will still not go up with the new combined Harvester Grabber System. It is roughly twice the weight of the previous grabber. Will has spent the last 4 days working with what seems to be every possible set of elastics, and below is a list of different things that we have tried.

The Donated Stress bands From Chris Rininger
The New Therabands which are currently being used
The black elastic tubing that we have used in the past, which is being used in conjunction with the Therabands

All have failed to resolve the issue of the scissor lift not going up or coming down if it does go up, or neither.

Today we have tried adding in a steel cable to the elastics to limit the use of some of the elastics similar to the loops we have used in the past. This may have worked a little as it seemed to get us close to something, but we’re still not there yet. Currently we have a plan to try and do two of these to get a stronger initial push, but then decrease once the scissor is moving up. I would like to try this in the first hour of Monday.

Other ideas that have been floated are

Using a pneumatic or a motor as a kicker to give the scissor lift a little initial boost. -
Mechanics don’t think we have enough time to do this (at the meeting today it was decided we abandon the combined system when we had to go to this)
Power Down --Tested, along with unseating the pneumatics it doesn't provide enough power (admittedly we used the pneumatics test rig, but almost nothing happened so it is no longer viable)
Using a motor to pull the scissor lift down --Three different people have thought of this, but we don’t have the time to design the system like the pneumatic kicker.
Removing weight from the Harvester Grabber - No, anything we remove right now is negligible in the mass of the grabber.

We’re currently looking for a simple solution that doesn’t require a lot of mechanical construction time. So if anyone has an idea, or wants more details on what has been tried, please say something that might get us heading in a direction.

But if we cannot get any of these ideas working in the first two hours on Monday, I would say we need to run with what we have currently, as we have a reliable and tested solution for the robot. While the older design is less than ideal, the drive team has experience using it, and we know it works, rather than trusting in a new design that may or may not work once we put it on the primary robot. Even if we get this new combined system functional there is no guarantee that it will increase our performance, especially if we are still debugging. I would say that we have almost exhausted this design now, but there are still some simple things worth trying before we end it just yet. My current thought is that we need to give it up, and focus on improving our driving as much as possible.

So please give us ideas on how to improve this design, or why we shouldn't leave it.

John Sachs
John Sachs11:31 PM

Have you looked at using a constant force spring (www.vulcanspring.com)? We have several in the mechanics room. Same idea as the elastic bands, just want to get the scissor closer to neutral, making it easier for the pneumatic.

2018-03-31
Kenneth Wiersema
Kenneth Wiersema7:35 AM

We’ve looked at them, mostly throwing them out because we didn’t have anything big enough in the right force range, most of our longest constant force springs require too much force to get them moving. I might want to play with the idea a bit more, but both Will and my first instinct was that we were uncertain how to use them in this situation. Also, we don’t exactly want a constant force all the way up, more force to start the scissor lift going at the bottom, but less at the top, in order for the scissor lift to come back down.

Harrison
Harrison9:08 AM

Have you already thought about doing lighting holes on the harvester(if there is even space on the harvester to do that)

Kenneth Wiersema
Kenneth Wiersema9:10 AM

Lightings holes as said above won’t make a meaningful difference.

Kenneth Wiersema
Kenneth Wiersema9:10 AM

We’re talking half a pound maybe

Chris Rininger
Chris Rininger9:12 AM

I was just reading this about springs: https://www.sciencebuddies.org/science-fair-projects/references/linear-nonlinear-springs-tutorial#nonlinearsprings It seems like a more linear metal spring could work better than the latex if I’m thinking about it right. In the bag of stuff I donated I think I included an old school arm exerciser that uses metal springs instead of latex. If not, have it here.

Harrison
Harrison9:13 AM

Oh I didn't see it

Chris Rininger
Chris Rininger9:14 AM

If I have it here, I know where it is

Kenneth Wiersema
Kenneth Wiersema9:15 AM

I remember seeing something of the type in there, might we worth trying, but I think our current rational is that elastics are better, because they are more easily tuned than springs

Chris Rininger
Chris Rininger9:16 AM

Could use metal spring for most of the force and weaker elastics to tune - just brainstorming

Kenneth Wiersema
Kenneth Wiersema9:18 AM

Something to try certainly, but we need to have a point where we’re ending this, as I don’t think we can get this working by Portland.

Chris Rininger
Chris Rininger9:21 AM

Yes, at some point it’ll be better to seek gains elsewhere... driving practice, refining in-match strategy (we’ve lost several close matches - how might we have won them?), etc. Sounds like you all think we might be there

Paul Vibrans
Paul Vibrans9:23 AM

I think a spring installation alongside the scissor that pulls mostly upward is the solution. I will create a sketch and post it.

Kenneth Wiersema
Kenneth Wiersema9:26 AM

We haven’t tried that, I think. If it doesn’t get in the way with everything else that we have on the scissor.

Chris Rininger
Chris Rininger10:31 AM

Expanding on earlier post... assuming our latex elastics behave something like this & metal springs behave linearly, it does seem like using linear metal springs would help avoid being on the wrong end of the curve when the lift is at the top.

Will Hobbs
Will Hobbs10:33 AM

My one worry with the spring you brought is it is very stiff and also very long and may not fit when the scissor lift is all the way up

Chris Rininger
Chris Rininger10:38 AM

Not saying that's the right spring to try to use - coach may have others (for demonstrating oscillation, for example). I wonder what a segment of last year's gear peg spring would do. As you and Kenneth have indicated though, there's limited time to keep trying different things, and driving practice with whatever system we end up keeping (original or new) would also help reduce cycle times.

Will Hobbs
Will Hobbs12:46 PM

I looked at all the springs we have

Will Hobbs
Will Hobbs12:46 PM

They are to small or way to stiff

Mark Tarlton
Mark Tarlton2:13 PM

This explains what we were trying yesterday. This is a graph showing the forces that the elastic bands need to supply to lift the scissor and cube. It gives an idea of how much force is required to get the lift started. I think we were on the right track with very short bands connected to a cable to provide forces only during the first portion of the lift. What this graph shows is that a LOT of force is required at the start. I think this second band assembly should be something like 10" of cable and then multiple loops of band with the length of each loop being about 3". When the bands are fully stretched, they will be about 9" long with 10" of cable giving a total length of 19" . They provide about 30 lbs of force per loop. In addition, multiple loops that run the full length of the lift base are still required to provide assistance over the entire distance of the lift. In this case, the loops are about 6" or 7" long so that when stretched, they will be about 20" in length.

Paul Vibrans
Paul Vibrans3:51 PM

I have "V's" and steel shafts to try with more vertical lift springs. There is one for each robot. I need to know where they should be delivered.

Paul Vibrans
Paul Vibrans3:56 PM

A band across the ends of a V lifts almost vertically when the lift is bottomed so is much more effective than a horizontal band under the scissor. They should work together to get the performance we need.

Mark Tarlton
Mark Tarlton4:11 PM

That looks great! What did you have in mind for "tabs" that the Vs are screwed to? Are they Located that sit on top of the rails on either side of the Vs?

Mark Tarlton
Mark Tarlton4:12 PM

(stupid autocorrect). Are they Ls that sit on top of the rails on either side of the rails?

Paul Vibrans
Paul Vibrans4:31 PM

The tabs lap over the vertical outsides of the rails. There are removable plastic guards there now. They would have to come off.

Paul Vibrans
Paul Vibrans4:32 PM

The tabs are flat, not angles.

Paul Vibrans
Paul Vibrans4:38 PM

The edge of the V is supposed to align with the end of the rail but in any case the shaft should be centered in the V with the scissor down. It is the middle shaft, not the lowest shaft.

Mark Tarlton
Mark Tarlton4:53 PM

BTW, we haven't experimented with the elastics that help the flipper. I expect that will need help with the extra weight as well. Any thoughts on how to help there?

Paul Vibrans
Paul Vibrans5:03 PM

More bands on the flipper should do the trick.

I need to get the V's to someone today. I am not able to attend any robotics meetings before Portland.

Mark Tarlton
Mark Tarlton5:04 PM

I can come by and pick them up now if you like. I'm going in Monday

Enrique Chee
Enrique Chee5:06 PM

@Paul Vibrans On Mon 4/2 the team will be meeting from 10 am to 4 pm . You can drop off if this works for you . Otherwise maybe @Will Hobbs can pickup from your house . Let us know . Thanks

Enrique Chee
Enrique Chee5:07 PM

@Mark Tarlton thanks

Paul Vibrans
Paul Vibrans5:09 PM

@Mark Tarlton Picking them up now is best. 9034 Springwood.

Mark Tarlton
Mark Tarlton5:09 PM

Ok. I'm on my way now

Paul Vibrans
Paul Vibrans5:43 PM

I forgot to mention that the V's will need to have some pockets drilled into the bottom to clear screw heads.

Kenneth Wiersema
Kenneth Wiersema5:45 PM

We'll evaluate the parts Monday on whether we want to keep on working with improving the scissor lift or not. We need to have a conversation before Monday on when we want to stop working on the new grabber harvester, or do we keep on trying right up until the last minute.

2018-04-02
Mark Tarlton
Mark Tarlton4:24 PM

The new harvester/grabber is working well enough that we will try to use it at Portland (assuming the crooks that stole the robot yesterday return it by then). The elastics that assist the lift going up and down are still a bit tricky to get adjusted properly but the team was able to demonstrate most of the necessary behaviors. Hopefully we'll be able to dial it in at the competition.

Paul Vibrans
Paul Vibrans4:37 PM

That's good news.

Mark Tarlton
Mark Tarlton5:49 PM

Yes, it's still pretty rough but we can get better with time. We should be more competitive than at GP.

Terry Shields
Terry Shields10:29 PM

Kudos to the student team for putting in a lot of hours and having the guts to attempt a new intake-grabber design for Portland. It was a lot of coordinated effort between the sub-teams and continues to be plenty of trial-and-error to get the design to work smoothly. In the end I believe we have a faster and more robust cube delivery system. Even if the redesign of THEMIS does not work out perfectly I applaud the team for trying (and this would not have been possible without the second robot). Paul: the “V’s” are a clever solution. Mark & Chris: thanks for pursuing improvements.

Chris Rininger
Chris Rininger11:14 PM

@Terry Shields +1 Congrats to the team for facing challenges head on & endeavoring to improve! And also great job building the second robot that has enabled these efforts. The team has taken itself to a new level this year in my opinion. I'm excited for Portland!

2018-04-03
Rose Bandrowski
Rose Bandrowski8:52 AM

I'm super proud of you guys. Good job, lets make the most of what we've got!

2018-07-14
Paul Vibrans
Paul Vibrans3:08 PM

@Paul Vibrans has left the channel

2018-10-17
Cruz Strom
Cruz Strom5:31 PM

@Cruz Strom archived the channel